Plumbing with internal flow guides

ABSTRACT

A conduit assembly may comprise: a pipe; a plurality of hollow passages disposed through the pipe; and a plurality of flow guides disposed in the pipe, each flow guide in the plurality of flow guides at least partially defining a respective hollow passage in the plurality of hollow passages. The conduit assembly may act as a heat exchanger.

FIELD

The present disclosure relates to gas turbine engines, and, morespecifically, to a plumbing apparatus for a gas turbine engine.

BACKGROUND

A gas turbine engine typically includes a fan section, a compressorsection, a combustor section, and a turbine section. In general, duringoperation, air is pressurized in the fan and compressor sections and ismixed with fuel and burned in the combustor section to generate hotcombustion gases. The hot combustion gases flow through the turbinesection, which extracts energy from the hot combustion gases to powerthe compressor section and other gas turbine engine loads.

Gas turbine engines may include various cooling systems that employ heatexchangers. Bypass air may be directed across the heat exchangers as acooling fluid. The inlet piping of the heat exchanger (i.e., the bypassair exiting the heat exchanger) may partially block and/or adverselyheat up an engine bay. The piping may also cause pressure loss that mayotherwise be used to drive heat rejection in the heat exchanger.

SUMMARY

A conduit assembly is disclosed herein. The conduit assembly maycomprise: a pipe; a plurality of hollow passages disposed through thepipe; and a plurality of flow guides disposed in the pipe, each flowguide in the plurality of flow guides at least partially defining arespective hollow passage in the plurality of hollow passages, wherein:the plurality of hollow passages are configured to receive a firstfluid, the pipe is configured to receive a second fluid, and the conduitassembly is configured to transfer heat from the first fluid to thesecond fluid.

In various embodiments, the pipe may include a curved pipe portionhaving an inner radius portion and an outer radius portion, theplurality of flow guides disposed between the outer radius portion andthe inner radius portion. Each flow guide in the plurality of flowguides may comprise a radially inner wall and a radially outer wall. Theradially inner wall and the radially outer wall may at least partiallydefine a respective hollow passage in the plurality of hollow passages.The pipe may be a straight pipe portion. The pipe may include a tripstrip on a heat transfer surface. Each flow guide in the plurality offlow guides may be configured to guide the first fluid.

A conduit assembly is disclosed herein. The conduit assembly maycomprise: a pipe portion configured to receive a first fluid, the pipeportion including a trip strip on a heat transfer surface; and aplurality of hollow passages disposed through the pipe portion, theplurality of hollow passages configured to receive a second fluid.

In various embodiments, the conduit assembly may further comprise aplurality of flow guides disposed in the pipe portion, each flow guidein the plurality of flow guides configured to guide the first fluid.Each flow guide in the plurality of flow guides may at least partiallydefine a respective hollow passage in the plurality of hollow passages.The pipe portion may be a curved pipe portion having an inner radiusportion and an outer radius portion, the plurality of flow guidesdisposed between the outer radius portion and the inner radius portion.Each flow guide in the plurality of flow guides may comprise a radiallyinner wall and a radially outer wall. The radially inner wall and theradially outer wall may at least partially define a respective hollowpassage in the plurality of hollow passages. The pipe portion may be astraight pipe portion.

A gas turbine engine is disclosed herein. The gas turbine engine maycomprise: an outer engine case structure; an inner engine case structuredisposed radially inward from the outer engine case structure, the outerengine case structure and the inner engine case structure defining abypass duct configured to receive an airflow; a conduit assembly atleast partially disposed in the bypass duct, the conduit assemblycomprise a pipe and a plurality of hollow passages disposed through thepipe, the conduit assembly configured to receive a fluid, the pluralityof hollow passages configured to receive the airflow.

In various embodiments, the gas turbine engine may further comprise aheat exchanger in fluid communication with the conduit assembly. The gasturbine engine may further comprise a plurality of flow guides disposedin the pipe, each flow guide in the plurality of flow guides configuredto guide the fluid. The pipe may include a curved pipe portion having aninner radius portion and an outer radius portion, the plurality of flowguides disposed between the outer radius portion and the inner radiusportion. Each flow guide in the plurality of flow guides may comprises aradially inner wall and a radially outer wall. The radially inner walland the radially outer wall may at least partially define a respectivehollow passage in the plurality of hollow passages.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the figures, wherein like numerals denotelike elements.

FIG. 1 illustrates a cross-sectional view of an exemplary gas turbineengine, in accordance with various embodiments;

FIG. 2A illustrates a perspective view of a cooling system having aconduit assembly, in accordance with various embodiments;

FIG. 2B illustrates a cross-sectional view of a cooling system having aconduit assembly, in accordance with various embodiments;

FIG. 3 illustrates a cross-section of a perspective view of a conduitassembly, in accordance with various embodiments;

FIG. 4 illustrates a perspective view of a conduit assembly, inaccordance with various embodiments;

FIG. 5 illustrates a front view of a conduit assembly, in accordancewith various embodiments;

FIG. 6 illustrates a front view of a conduit assembly, in accordancewith various embodiments; and

FIG. 7 illustrates a top view of various cooling features formable on aheat transfer surface of a conduit assembly, in accordance with variousembodiments.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration. While these exemplary embodiments are described insufficient detail to enable those skilled in the art to practice theexemplary embodiments of the disclosure, it should be understood thatother embodiments may be realized and that logical changes andadaptations in design and construction may be made in accordance withthis disclosure and the teachings herein. Thus, the detailed descriptionherein is presented for purposes of illustration only and notlimitation. The steps recited in any of the method or processdescriptions may be executed in any order and are not necessarilylimited to the order presented.

Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact. Surface cross hatching lines may be used throughoutthe figures to denote different parts but not necessarily to denote thesame or different materials.

Throughout the present disclosure, like reference numbers denote likeelements.

Accordingly, elements with like element numbering may be shown in thefigures, but may not necessarily be repeated herein for the sake ofclarity.

As used herein, “aft” refers to the direction associated with the tail(e.g., the back end) of an aircraft, or generally, to the direction ofexhaust of a gas turbine engine.

A first component that is “radially outward” of a second component meansthat the first component is positioned at a greater distance away from acentral longitudinal axis of the gas turbine engine. A first componentthat is “radially inward” of a second component means that the firstcomponent is positioned closer to the engine central longitudinal axisthan the second component. The terminology “radially outward” and“radially inward” may also be used relative to reference axes other thanthe engine central longitudinal axis.

In various embodiments and with reference to FIG. 1, a gas turbineengine 20 is provided. Gas turbine engine 20 may generally include a fansection 22, a compressor section 24, a combustor section 26, and aturbine section 28. In operation, fan section 22 drives fluid (e.g.,air) along a bypass flow-path B, while compressor section 24 drivesfluid along a core flow-path C for compression and communication intocombustor section 26 and then expansion through turbine section 28.Although gas turbine engine 20 is depicted as a turbofan gas turbineengine herein, it should be understood that the concepts describedherein are not limited to use with turbofans as the teachings may beapplied to other types of turbine engines.

Gas turbine engine 20 may generally comprise a low speed spool 30 and ahigh speed spool 32 mounted concentrically, via bearing systems 38, forrotation about for rotation about engine central longitudinal axis A-A′and relative to an engine static structure 36. It should be understoodthat various bearing systems 38 at various locations may alternativelyor additionally be provided, including for example, bearing system 38,bearing system 38-1, and bearing system 38-2. Engine centrallongitudinal axis A-A′ is oriented in the z direction on the providedxyz axes. The z direction on the provided xyz axes refers to the axialdirection. As used herein, the term “radially” refer to directionstowards and away from engine central longitudinal axis A-A′ and thez-axis. As used herein, the terms “circumferential” and“circumferentially” refer to directions about central longitudinal axisA-A′ and the z-axis.

Low speed spool 30 may generally comprise an inner shaft 40 thatinterconnects a fan 42, a low pressure compressor 44, and a low pressureturbine 46. Inner shaft 40 may be connected to fan 42 through a gearedarchitecture 48 that can drive fan 42 at a lower speed than low speedspool 30. Geared architecture 48 may comprise a gear assembly 60enclosed within a gear housing 62. Gear assembly 60 couples inner shaft40 to a rotating fan structure. High speed spool 32 may comprise anouter shaft 50 that interconnects a high pressure compressor 52 and highpressure turbine 54. A combustor 56 may be located between high pressurecompressor 52 and high pressure turbine 54. A mid-turbine frame 57 ofengine static structure 36 may be located generally between highpressure turbine 54 and low pressure turbine 46. Mid-turbine frame 57may support one or more bearing systems 38 in turbine section 28. Innershaft 40 and outer shaft 50 may be concentric and rotate via bearingsystems 38 about engine central longitudinal axis A-A′, which iscollinear with their longitudinal axes. As used herein, a “highpressure” compressor or turbine experiences a higher pressure than acorresponding “low pressure” compressor or turbine. The airflow in coreflow-path C may be compressed by low pressure compressor 44 and highpressure compressor 52, mixed and burned with fuel in combustor 56, thenexpanded over high pressure turbine 54 and low pressure turbine 46.Turbines 46, 54 rotationally drive the respective low speed spool 30 andhigh speed spool 32 in response to the expansion.

The compressor section 24, the combustor section 26, and the turbinesection 28 are generally referred to as the engine core. Air is drawninto gas turbine engine 20 through fan 42. Air exiting fan 42 may bedivided between core flow-path C and bypass flow-path B. The airflow inbypass flow-path B may be utilized for multiple purposes including, forexample, cooling and pressurization.

Referring to FIG. 2A, and with continued reference to FIG. 1, a coolingsystem 100 having a conduit assembly 200 is illustrated, in accordancewith various embodiments. Cooling system 100 includes one or more heatexchanger(s) 104. Heat exchanger(s) 104 may be located between an outerengine case structure 106 and an inner engine case structure 108. Outerengine case structure 106 is radially outward of inner engine casestructure 108. Outer engine case structure 106 and inner engine casestructure 108 may define a generally annular bypass duct 102 around theengine core. In various embodiments, inner engine case structure 108 mayform a portion of engine static structure 36. In various embodiments,air discharged from, for example, fan section 22 may be communicatedthrough the bypass duct 102.

Heat exchanger 104 and conduit assembly 200 are configured to receive acooling airflow, for example, airflow 124. In various embodiments,airflow 124 may be a portion of the bypass airflow in bypass duct 102.Cooling airflow 124 may be directed across heat exchanger 104 to coolthe air in heat exchanger 104 and/or conduit assembly 200. Airflow 124flows across and/or through heat exchanger 104 to cool the air providedby inlet conduit 112. Airflow 124 is then output from an exhaust output129 of heat exchanger 104. Stated differently, heat exchanger 104receives airflow 124 (i.e. a portion of the airflow in bypass duct 102)at cooling flow input 126 and outputs airflow 124 at exhaust output 129.Similarly, airflow 124 flows through a portion of conduit assembly 200,as described further herein.

Referring now to FIG. 2B, an axial cross-sectional view of coolingsystem 100 is illustrated, in accordance with various embodiments. Invarious embodiments, the cooling system further comprises a conduitassembly 202. In various embodiments, conduit assembly 200 may be aninlet conduit and conduit assembly 202 may be an outlet conduit. In thisregard, relatively hot air may be routed from compressor section 24,travel through the inlet conduit (e.g., conduit assembly 200), throughthe heat exchanger 104, through the outlet conduit (e.g., conduitassembly 202) and routed to a stage in the turbine section 28.

Referring to FIG. 3, a cross-sectional view of a conduit assembly 200 isillustrated, in accordance with various embodiments. In variousembodiments, conduit assembly 202 from FIG. 2B may be in accordance withconduit assembly 200. In various embodiments, the conduit assemblycomprises a first straight pipe portion 210, a second straight pipeportion 220 and a curved pipe portion 230 disposed between firststraight pipe portion 210 and second straight pipe portion 220. Invarious embodiments, the curved pipe portion 230 comprises a pluralityof flow guides 240. Each flow guide in the plurality of flow guides 240may extend from a first side of the flow guide to a second side of theflow guide. In this regard, a hollow portion of each flow guide may beconfigured to receive an airflow, such as airflow 124 form a bypass ductas shown in FIGS. 2A and 2B.

In various embodiments, curved pipe portion 230 comprises an innerradius curve portion 232 disposed opposite an outer radius curve portion234. The plurality of flow guides 240 may be disposed between the innerradius curve portion 232 and the outer radius curve portion 234. Forexample, a first flow guide 241 may be disposed radially outward frominner radius curve portion 232. First flow guide 241 may comprise aradius of curvature that is greater than a radius of curvature of theinner radius curve portion 232. In various embodiments, a second flowguide 242 may be disposed radially outward from first flow guide 241. Athird flow guide 243 may be disposed radially outward from second flowguide 242, a fourth flow guide 244 may be disposed radially outward fromthird flow guide 243, a fifth flow guide 245 may be disposed radiallyoutward form the fourth flow guide 244, a sixth flow guide 246 may bedisposed radially outward from the fifth flow guide 245, and/or aseventh flow guide 247 may be disposed radially outward from the sixthflow guide 246. The seventh flow guide 247 may be disposed radiallyinward form the outer radius curve portion 234.

In various embodiments, the closer a flow guide is to the outer radiuscurve portion 234 the greater an arc length of the flow guide. Forexample, second flow guide 242 may have a greater arc length than thefirst flow guide 241, the third flow guide 243 may have a greater arclength than the second flow guide 242, etc. Each flow guide in theplurality of flow guides may comprises a radially inner wall and aradially outer wall.

In various embodiments, the curved pipe portion 230 may be manufacturedusing additive manufacturing, casting, or the like. In variousembodiments, the first straight pipe portion 210 and the second straightpipe portion 220 may comprise a stock pipe or the like. In variousembodiments, the curved pipe portion 230 may be coupled to the firststraight pipe portion 210 and the second straight pipe portion bywelding, brazing, or the like.

For example, with reference to FIG. 4, first flow guide 241 may comprisea radially inner wall 311 disposed proximate the inner radius curveportion 232 of the curved pipe portion 230. The first flow guide 241 mayfurther comprise a radially outer wall 312 disposed radially outwardfrom the radially inner wall 311. The radially inner wall 311 may becoupled to the radially outer wall 312 at a first end 313 disposedproximate the first straight pipe portion 210 of the conduit assembly200. Similarly, the radially inner wall 311 may be coupled to theradially outer wall 312 at a second end 314 disposed proximate thesecond straight pipe portion 220. In various embodiments the first end313 and the second end 314 may comprise rounded ends, straight ends, orthe like. In various embodiments, the radially inner wall 311, theradially outer wall 312, the first end 313 and the second end 314 maydefine a hollow passage 315 therethrough. In various embodiments, theconduit assembly 200 may be configured to receive a first fluid flowingtherethrough and the hollow passage 315 may be configured to receive asecond fluid flowing therethrough. The first fluid and the second fluidmay flow independent of each other. In this regard, with brief referenceto FIGS. 2 and 3, in accordance with various embodiments, an airflow 124in a bypass air duct may flow through the hollow passage 315 of firstflow guide 241 and a secondary airflow 324 may flow through conduitassembly 200. In various embodiments, each flow guide in the pluralityof flow guides 240 may be in accordance with first flow guide 241.

In various embodiments, the hollow passages defined by the plurality offlow guides 240 may act as a heat exchanger. Each hollow passageway maycomprise an inlet and an outlet. For example, with reference now to FIG.5, the seventh flow guide 247 may comprise an inlet 411 and an outlet412. The inlet 411 may be configured to receive an airflow, such asairflow 124 from FIGS. 2A and 2B in a bypass duct 102. Cooling airflow124 may be directed across the plurality of flow guides 240 to cool theair in conduit assembly 200. Airflow 124 flows across and/or throughhollow passageways defined by the plurality of flow guides 240 to coolthe air provided by inlet conduit 112 from FIGS. 2A and 2B. Airflow 124is then output from the outlet 412 of hollow passageway 415 defined bythe seventh flow guide 247. Stated differently, conduit assembly 200receives airflow 124 (i.e. a portion of the airflow in bypass duct 102)at inlet an inlet of each hollow passageway defined by the plurality offlow guides (e.g., hollow passageway 415) and outputs airflow 124 at theoutlet of each hollow passageway defined by the plurality of flow guides(e.g., outlet 412).

Referring now to FIG. 6, conduit assembly 600 in accordance with variousembodiments is illustrated. In various embodiments, the plurality offlow guides, as described in FIGS. 3-5 may be disposed in a straightportion of a conduit assembly. For example, conduit assembly 600comprises a plurality of flow guides 640 disposed in a straight pipeportion 610 of conduit assembly 600. The plurality of flow guides 640may be in accordance with the plurality of flow guides 240 as describedin FIGS. 3-5. In this regard, walls defined by the plurality of flowguides 640 may define a plurality of hollow passages 650 disposedthrough straight pipe portion 610. In accordance with variousembodiments, the conduit assembly 600 may act as a heat exchanger in asimilar manner as described with respect to conduit assembly 200. Invarious embodiments, any combination of straight pipe portion 610 andcurved pipe portion 230 from FIGS. 3-5 may be used in combination asdesired. In various embodiments, a combination of conduit assembly 600and conduit assembly 200 may allow for a reduced size heat exchanger 104in FIGS. 2A and 2B relative to typical heat exchangers as a result ofconduit assembly 200 and/or conduit assembly 600 acting as a heatexchanger. In various embodiments, conduit assembly 200, conduitassembly 600, and/or any combination thereof may eliminate a heatexchanger 104 in FIGS. 2A and 2B when enough heat transfer is providedby the conduit assembly.

Referring now to FIG. 7, exemplary trip strip geometries are shown for aheat transfer surface 702 of a conduit assembly (e.g., conduit assembly200 or conduit assembly 600) according to various embodiments. The heattransfer surface 702 may be an internal surface of a conduit assembly oran external surface of the conduit assembly based on the application.The trip strips may be positioned on any surface internal to a conduitassembly (e.g., conduit assembly 200 or conduit assembly 600), forexample. A trip strip 760, 762, 764, 766, 768 may protrude from aninternal surface of conduit assembly 200 of straight pipe portion 210,curved pipe portion 230, straight pipe portion 220 and/or any flow guidein the plurality of flow guides 240. Similarly, the trip strip 760, 762,764, 766, 768 may protrude from an internal surface of conduit assembly600. In this regard, the trip strip 760, 762, 764, 766, 768 may enhancea heat transfer coefficient within the conduit assembly (e.g., conduitassembly 200, 600) relative to typical conduit assemblies.

In various embodiments, elongated trip strip 760 may be parallel to oneanother and have similar dimensions. Elongated trip strip 762 may alsoprotrude from any internal surface of a respective conduit assembly(e.g., conduit assembly 200, 600). Elongated trip strip 762 may beangled relative to one another such that the trip strips arenon-parallel. Elongated trip strip 762 may also have similar dimensions.

In various embodiments, s-shaped trip strips 764 may protrude from anyinternal surface of a respective conduit assembly (e.g., conduitassembly 200, 600). S-shaped trip strips 764 may have an undulatinggeometry similar to a sine wave, for example. S-shaped trip strips 764may be formed in pairs having similar geometry and dimensions. S-shapedtrip strips 764 may also be oriented individually. Chevron trip strip766 may also protrude from any internal surface of a respective conduitassembly (e.g., conduit assembly 200, 600). Chevron trip strips 766 mayhave a v shape and may be oriented with the point of the v shapedirected generally upstream or downstream. Pedestal trip strips 768 mayprotrude from any internal surface of a respective conduit assembly(e.g., conduit assembly 200, 600). Pedestal trip strips may be formedhaving varied or similar geometries and dimensions. Pedestal trip stripsmay also have varying pitch density.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various FIGS. contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosures. The scope of the disclosures is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”, “anexample embodiment”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element is intended to invoke 35 U.S.C. 112(f)unless the element is expressly recited using the phrase “means for.” Asused herein, the terms “comprises”, “comprising”, or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus.

What is claimed is:
 1. A gas turbine engine, comprising: an outer enginecase structure; an inner engine case structure disposed radially inwardfrom the outer engine case structure relative to a longitudinal axis ofthe gas turbine engine, the outer engine case structure and the innerengine case structure defining a bypass duct configured to receive anairflow; a conduit assembly at least partially disposed in the bypassduct, the conduit assembly comprising: a pipe defined by an annular wallof constant diameter, a length of the pipe being curved with a center ofcurvature outside of the pipe to form a curved pipe portion; a pluralityof hollow passages defined by a plurality of flow guides in the curvedpipes portion, each hollow passage of the plurality of hollow passagesextending from an inlet formed through the annular wall in the curvedpipe portion to an opposing outlet formed through the annular wall inthe curved pipe portion, each flow guide of the plurality of flow guidesat least partially defining a respective hollow passage of the pluralityof hollow passages, wherein the pipe is configured to receive a fluid,and the plurality of hollow passages are configured to receive theairflow, wherein: the plurality of flow guides comprises a first flowguide and a second flow guide, the second flow guide is disposedradially outward from the first flow guide relative to the center ofcurvature, the second flow guide has a second arc length greater than afirst arc length of the first flow guide, and the first flow guide andthe second flow guide are each configured to turn the fluid in theconduit assembly through the curved pipe portion of the pipe.
 2. The gasturbine engine of claim 1, further comprising a heat exchanger in fluidcommunication with the conduit assembly.
 3. The gas turbine engine ofclaim 1, wherein, each flow guide of the plurality of flow guides isconfigured to guide the fluid.
 4. The gas turbine engine of claim 1,wherein each flow guide of the plurality of flow guides comprises aradially inner wall and a radially outer wall with respect to the centerof curvature.
 5. The gas turbine engine of claim 4, wherein: theradially inner wall and the radially outer wall of each flow guide ofthe plurality of flow guides, together, at least partially define arespective hollow passage of the plurality of hollow passages, and boththe radially inner wall and the radially outer wall of each flow guidein the plurality of flow guides are only associated with a single hollowpassage of the plurality of hollow passages.
 6. The gas turbine engineof claim 1, wherein the plurality of flow guides further comprises athird flow guide disposed radially outward of the second flow guiderelative to the center of curvature, the third flow guide having a thirdarc length that is greater than the first arc length and the second arclength.